A local sheriff told ABC News yesterday that the firefighters, paramedics and other workers trying to put out the initial fire that likely caused the explosion "didn't have a chance."

The cause of the blast that injured 200 people is still under investigation. A fire was reported at the plant at 7:29 p.m., and the first call of the explosion came in less than 30 minutes later. First responders began evacuating the area as soon as they got to the fire.

About 60 people are still missing after the explosion. McLennan County Judge Scott Felton told the AP that many of those unaccounted for probably lost their homes and have been difficult to locate.

ABC News called the explosion "one of the greatest losses of first responders" since a 2007 factory fire that killed nine in Charleston, S.C.